In-flight refueling (or air-to-air refueling) is an important method for extending the range of both manned and unmanned aircraft traveling long distances over areas having no feasible landing or refueling points. Although in-flight refueling is a relatively common operation, especially for military aircraft, the passage of large amounts of fuel between a first aircraft (serving, for example, as a tanker aircraft) and second aircraft during an in-flight refueling operation may create a potentially dangerous situation, especially if components of the in-flight refueling system separate and/or fail in an uncontrolled manner.
One conventional system for in-flight refueling is the probe and drogue in-flight refueling system wherein the tanker aircraft may extend a flexible hose having an end attached to a drogue such that the second aircraft having a refueling probe, may engage the drogue while in flight in order to initiate the transfer of fuel. An operator of the second aircraft is responsible for maneuvering the second aircraft such that the refueling probe extending therefrom may enter and engage the drogue. According to some conventional probe and drogue in-flight refueling systems, the engagement of the refueling probe with the drogue is accomplished as the second aircraft accelerates with respect to the trailing drogue. The drogue may include, for, instance, a catch mechanism for securing the refueling probe within the drogue so that the refueling probe may be securely fastened within the drogue during the transfer of fuel.
At the conclusion of the in-flight refueling operation, the operator of the second aircraft may control the second aircraft such that the second aircraft may decelerate with respect to the trailing drogue such that a separating force is exerted on the refueling probe such that the refueling probe may be disengaged from the drogue and/or the catch mechanism within the drogue. The operator of the second aircraft is responsible for decelerating the second aircraft in a controlled manner so as to safely disengage the refueling probe from the drogue without introducing excessive tension or shear forces to the trailing hose or components of the in-flight refueling system that may be disposed within a fuselage of the tanker aircraft or in a pod hanging, for instance, on a wing hardpoint of the tanker aircraft. In some cases, however, the catch mechanism within the trailing drogue may malfunction such that the refueling probe may not be disengaged from the trailing drogue without subjecting the hose and/or other in-flight refueling system components to an excessive tension or shear force.
In such cases, conventional probe and drogue in-flight refueling systems may provide a guillotine system disposed, for instance, in the fuselage of the tanker aircraft, for jettisoning the hose from the tanker aircraft. More particularly, a guillotine blade may be configured to be capable of cutting the hose at a point inside or near the fuselage of the tanker aircraft such that the hose may fall away from the tanker aircraft. In addition, the guillotine may block the fuel conduit defined within the remaining length of hose and may further, in cooperation with fuel shut-off valves disposed within the tanker aircraft, prevent additional fuel from flowing from the tanker aircraft. If the guillotine system is used, however, the jettisoned portion of the hose may still hang from the refueling probe of the second aircraft such that a long section of loose hose may be left trailing from the refueling probe. Such a situation may be extremely dangerous for the operator of the second aircraft, as the remaining section of hose may oscillate uncontrollably with respect to the second aircraft and may strike and shatter a windscreen of the second aircraft or strike and damage a control surface of the second aircraft. Additionally, if the second aircraft is a jet powered aircraft, the remaining section of hose may be drawn into a jet intake of the second aircraft and damage one or more of the engines of the second aircraft.
If the catch mechanism of the drogue malfunctions as described above, the operators of the first and second aircraft, may also confer and decide to attempt to land the first and second aircraft in unison so as to prevent the need for jettisoning the hose. This option, however, may also be extremely dangerous, given the precision required to maintain the second aircraft in a position relative to the tanker aircraft so as to safely land the aircraft in unison. In addition, this option may not be available if, for instance, the in-flight refueling operation is underway far away from an available airfield. It is this situation that presents the need to conduct in-flight refueling operations in the first place. In addition, such a landing may be impossible in cases where the first and second aircraft may have significantly different stall characteristics.
Thus, it would be advantageous to provide an alternative method for disengaging the hose and/or drogue from a refueling probe of a second aircraft should the refueling probe of the second aircraft be unable to be safely disengaged from the drogue during an in-flight refueling operation. In addition, it would be advantageous to provide a separating mechanism that may separate the drogue from the hose carried by the tanker aircraft in a controlled and predictable manner so as to avoid the dangerous situations described in more detail above. It would be especially advantageous to provide a separating mechanism disposed between an end of the hose and the drogue of a probe and drogue in-flight refueling system such that upon the exertion of a separating force, the hose may separate from the drogue such that a severed portion of hose may be less likely to hang from the refueling probe (and the drogue attached thereto) of the second aircraft. Thus, the second aircraft may safely extract itself from a refueling connection with the tanker aircraft leaving only the drogue attached to the refueling probe.
Therefore, there exists a need for a mechanical fuse device and method for facilitating controlled separation of in-flight refueling system components that may be installed in a probe and drogue in-flight refueling system. More particularly, there exists a need for a mechanical fuse device that may be disposed between selected components of a probe and drogue in-flight refueling system such that the mechanical fuse device may be configured to be capable of separating in a controlled and predictable manner such that a second aircraft may safely disengage from the probe and drogue in-flight refueling system carried by a tanker aircraft even in cases where, for instance, an in-flight refueling probe carried by the second aircraft may not be capable of disengaging from a drogue trailing from the tanker aircraft.